ANAT Block theory #2 Flashcards
(176 cards)
1
Q
What are the three steps of the nervous system?
A
- Sensory input
- Integration
- Motor output
2
Q
What is sensory input?
A
Sensory input from the environment is detected by sensory nerves and travels through the body to communicate with other nerve cells
3
Q
What is integration?
A
Processing and interpretation of sensory input
4
Q
What is motor output?
A
a response to integrated stimuli; the response activates muscles or glands by sending motor output through motor nerves
5
Q
What are the two principal subdivisions of the nervous system?
A
Central
Peripheral
6
Q
What is the function of the CNS?
A
»Where all signals come to and from
»Where they are integrated
»Where information can be stored
7
Q
What is the function of the PNS?
A
System that brings those signals to and from the CNS
8
Q
What are the two divisions that the PNS can be further broken down into?
A
Sensory (afferent) division
Motor (efferent) division
9
Q
What does the sensory division do?
A
Relays information to CNS
Sensing things such as sight, smell, touch and even pain
Sends the information to the CNS through sensory neurons
10
Q
What does the motor division do?
A
Relays information from CNS to target cells
The actual response that is elicited
Signal comes from the CNS, the brain, or spinal cord and is relayed to a target cell through efferent neurons
11
Q
What subdivisions can the motor (efferent) division be further divided into?
A
Somatic
Autonomic
12
Q
What is the function of the somatic nervous system? And how does it do that?
A
Controls voluntary movement
Signal comes from the CNS through the efferent neurons to a target skeletal muscle cell, eliciting movement of that muscle
13
Q
What is the function of the autonomic nervous system?
A
Controls involuntary movement
14
Q
What can the autonomic nervous system be further divided into?
A
Sympathetic - fight or flight
Parasympathetic - rest and digest
15
Q
What do neurons do?
A
Structural units of the nervous system.
Allow for communication within and between the CNS and PNS.
Can generate and transmit rapid electrical signals to other neurons
16
Q
Neuron Structure
A
cell body, dendrites, axon
17
Q
What does the cell body do in a neuron?
A
Functions to transfer electrical signals from the dendrites to the axon
Also called the ‘soma’
Houses the nucleus and other organelles
18
Q
What does the dendrites do in a neuron?
A
Receive the neuronal signal form other neurons and transfer those signals to the cell body
19
Q
What does the axon do in a neuron?
A
Carry the signal from the cell body to the axon terminals, where the signal is then transferred to other neurons or organs
20
Q
What is the direction of a nerve impulse?
A
Unidirectional
21
Q
What are the characteristics of a pseudo-unipolar neuron?
A
Have one cellular process that splits into a dendrite and an axon.
Example: general sensory nerves
22
Q
What are the characteristics of a bipolar neuron?
A
Have one dendrite and one axon that extend directly from the cell body
Have two distinct cellular processes
Only found in special sense, like sight and hearing
23
Q
What are the characteristics of a multipolar neuron?
A
Have multiple dendrites and one axon, summing to three or more cellular processes
Number of dendrites is variable
Most common type of neurons
Example: motor neurons
24
Q
What is the function of glia?
A
- Function to protect and support neurons and aid in sending signals between neurons to improve communication
- These cells DO NOT generate or transmit nerve impulses
24
What are the 4 supporting cells of the CNS?
1. Astrocytes
2. Microglia
3. Ependymal
4. Oligodendrocytes
25
What is an astrocyte?
- Large star shaped cells with numerous processes
- Communicate with neurons and blood vessels to maintain the integrity of the neural tissue
- Most abundant
26
What is microglia?
-Perform many protective functions in the CNS
-Able to phagocytose, or engulf and destroy pathogens, and eliminate waste products from other cells
-Least common
27
What is ependymal?
-Cuboidal in shape
-Line cavities of brain and spinal cord
-Assist in the production, circulation, and monitoring of cerebrospinal fluid (CSF)
28
What are oliogodendrocytes?
Wrap around axons in the CNS to form myelin sheath
29
What is myelination?
-An important function of neuroglia is to myelinate parts of an axon
-Myelin is composed mainly of fat
-Appears white
-Insulates the axon and increases the speed at which electrical signals can travel down the axon
30
What are unmyelinated axons called?
Nodes of Ranvier
31
What is the main type of neuroglial cell in the PNS called?
The Schwann Cell
32
What is a Schwann cell?
They wrap the axon with myelin sheath. These are found in the PNS and only myelinate one axon at a time.
33
What parts is the brain composed of?
Cerebrum
Brainstem
Cerebellum
34
What makes up the bulk of the brain?
Cerebrum
35
What is the telencephalon?
A part of the cerebrum
36
What are the features of the Telencephalon?
Cerebral hemisphere
Cerebral cortex
Sulci and gyri
37
What is the cerebral hemisphere?
-Cerebrum is made up of two paired hemispheres: the right and the left cerebral hemisphere
-Hemispheres are separated by the longitudinal fissure
38
What is the cerebral cortex?
outer layer of the cerebrum - can be distinguished by its dark, grey colour
39
What are the sulci and gyri?
-Folds in the cerebrum
-Increases surface area of neural tissue which increase the functional capacity of the tissue
-Fissures and grooves: sulci
-Lumps and bumps: gyri
40
Where is the pre-central sulcus?
running in front of and parallel to the central sulcus, separated from it by the precentral gyrus.
41
Where is the lateral sulcus?
between temporal and parietal/frontal lobes
42
Where is the parieto-occipital sulcus?
between parietal and occipital lobes
42
Where is the post-central sulcus?
parallel to, and behind, the central sulcus in the human brain.
43
Where is the central sulcus?
between frontal and parietal lobes - it also separates the motor from the sensory cortex
44
What does the pre-central gyrus do?
Responsible for sending motor output signals. It is located anteriorly to the central sulcus
45
What does the post-central gyrus do?
Responsible for sending motor output signals. It is located anteriorly to the central sulcus
46
What does the post-central gyrus do?
Responsible for receiving sensory input related to touch and feel. It is located posteriorly to the central sulcus
47
What are the four lobes?
frontal, parietal, temporal, occipital
48
Grey Matter of the brain
-Consists of nerve cell bodies, short interneurons, and glial cells
-Contains the central canal which is filled with CSF
-Each half of the grey matter is divided into regions called horns
-Can be found in cerebral cortex and inner areas of the brain
49
What does the ventral horn do?
carries motor information
50
What does the dorsal horn do?
carries sensory information
51
White matter of the brain
-Lines the outside of the grey matter of the spinal cord (but is on the inside of the brain)
-Consists of bundles of nerve fibres or axons
-Consists of tracts of fibres separated into anterior, lateral, and posterior funiculi (bundles)
-Each bundle is connected to a specific region of the brain
52
What are the three categories of white matter tracts?
1. Association
2. Commissural
3. Projection Fibres`
53
What does the association fibres do?
Facilitate communication within ONE hemisphere
54
What does the commissural fibres do?
facilitate communication between two hemispheres
e.g. corpus callosum
55
What does the projection fibres do?
Facilitate communication between different levels of the CNS
E.g. between brain and spinal cord
56
What are the components of the Diencephalon of the cerebrum?
-Thalamus
-Hypothalamus
57
What is the thalamus?
»Deep brain structure with two bodies (one per hemisphere)
»Responsible for relaying sensory information (except the sense of smell) to other areas of the brain
58
What is the hypothalamus?
»Small structure below the thalamus
»Connected to pituitary gland
»Controls the release of hormones through the pituitary gland
59
What is the brainstem?
Area of the brain that connects the brain to the spinal cord
Situated just below the diencephalon
60
What is the brainstem comprised of?
comprised of?
midbrain, pons, medulla
61
What is the midbrain?
*Most superior aspect of the brainstem
*Anteriorly, the midbrain consists of large white matter tracts that make up the cerebral peduncles
*Postero-lateral view: midbrain has two pairs of raised bumps, known as the superior and inferior colliculi
62
What is the pons?
*Structure in the middle of the brainstem
*Located anterior to the 4th ventricle and the cerebellum
*Pons has fibers connecting it to the cerebellum, allowing for communication between these two structures
63
What is the medulla oblongata?
*Most inferior structure
*Continuous with the spinal cord
64
Where is the cerebellum located?
Structure that is appended to the back of the brainstem
Sits underneath the occipital lobe of the cerebrum
65
What does the cerebellum do?
coordinates movement and balance
66
What are meninges?
dura mater, arachnoid mater, pia mater
67
What do the meninges do?
They serve as a protective covering of the CNS
68
What is the dura mater?
Dura Mater is the most superficial and tough of the meninges. It is composed of a double layer of connective tissue that attaches firmly to the skull
69
What is the arachnoid mater?
*Loosely covers the brain
*Creates an area called the subarachnoid space
*This space is filled with cerebrospinal fluid (a protective fluid) and blood vessels
70
What is the pia mater?
This is the internal layer that attaches to the cerebral cortex
71
What do the ventricles do?
Support and protection to the brain
72
What are the ventricles in the brain made up of?
»Made up of four hollow spaces that are continuous with each other and the spinal cord
»Spaces contained cerebrospinal fluid (CSF
73
Lateral ventricles
*Lateral ventricles are paired "c" shaped spaces deep within the cerebral hemisphere
*Portion of the lateral ventricles can be found in each lobe
74
Third ventricle
-The singular third ventricle is located in the middle of the diencephalon between the two halves of the thalamus.
-Connected to the lateral ventricles by the interventricular foramina (of Monro)
75
Fourth ventricle
-Sits between the pons/medulla and the cerebellum
-Connected to the third ventricle by the cerebral aqueduct
-Continuous with the central canal of the spinal cord and the subarachnoid space
76
How many ventricles are in the brain?
1. Lateral ventricles (2)
2. Fourth ventricle (1)
3. Third ventricle (1)
*All together 4
77
What is the directional flow of CSF?
1. Lateral Ventricles
2. Interventricular Foramen
3. Third ventricle
4. Cerebral Aqueduct
5. Fourth Ventricle
6. Subarachnoid space
78
Where is the spinal cord located?
vertebral canal and is supported by the vertebral column
79
What is the purpose of the spinal cord?
Facilitates communication between the central nervous system and peripheral nervous system through the spinal nerves
80
Where does the spinal cord begin?
foramen magnum
81
Where does the spinal cord end?
L2
82
What happens below the L2 level?
Inferior to L2, the axons emerging from the spinal cord are known as the cauda equina
Within the cauda equina, the filum terminale (a small thin strand of pia mater) anchors the spinal cord to the sacrum
83
Order of spinal cord regions from top to bottom
Cervical, thoracic, lumbar sacral
84
Why do spinal enlargements occur?
Enlargements occur because of the additional nerves exiting the spinal cord that supply the limbs
85
Where is the spinal cord enlarged?
cervical and lumbar regions
86
What does the cervical enlargement supply?
upper limbs
87
What does the lumbar enlargement supply?
lower limbs
88
When the C1 to C3 are injured what happens?
Limited movement of the head and neck only
89
When the C5 is injured, what happens?
Head, neck, and shoulder movement, bend elbows and rotate hands
90
What is injured when there is normal upper body movement, but some degree of impairment in the legs?
T1-T6 injury
91
Where is the grey matter of the spinal cord located?
inside
92
What does the grey matter in the spinal cord consist of?
Consists of a ventral horn (which carries motor information), and a dorsal horn (which carries sensory information)
93
Where is the white matter of the spinal cord located?
White matter lines the outside of the grey matter of the spinal cord
94
Where is the white matter of the spinal cord consist of?
Consists of tracts of fibers separated into anterior, lateral, and posterior funiculi (bundles)
95
What is grey matter in the spinal cord composed of?
Mainly composed of dendrites, neuron cell bodies, glial cells, and unmyelinated axons
96
What is white matter in the spinal cord composed of?
Mainly composed of myelinated axons
97
What does the endocrine system work at?
Homeostasis
98
What is homeostasis?
Proper balance of chemicals and other substances in the body and the harmonious functioning and coordination of all the various bodily processes and organ systems
99
What does the endocrine system do?
System helps maintain state of balance in the body by performing a regulatory role for all the other organ systems by secreting hormones and glands
100
What are hormones?
Chemical messengers that travel through our circulatory system to other parts of the body in order to control or regulate a body process
101
Define endocrine
Cells of these glands secrete hormones directly into the interstitial fluid surrounding the secretory cells. The hormones are then picked up by the blood capillaries
Glands secrete their hormones within the gland
102
Define exocrine
Glands that secrete cell products into a duct system
Glands that secrete their hormones outside the gland
103
pituitary gland
-base of the brain that extends from the hypothalamus
-known as the "master gland"
-produces and releases hormones that control all other endocrine glands
104
thyroid gland
-produces thyroid glands important for homeostasis
-sits anterior to the trachea
-calcium homeostasis
105
parathyroid glands
-four small oval glands situated on the back of thyroid gland
-paired (2 superior, and 2 inferior)
-maintenance of calcium homeostasis
106
pancreas
Produces enzymes for digestion and the hormone insulin that regulates blood sugar levels
107
adrenal glands
-sit on top of each kidney
-"suprarenal glands"
-production of corticosteroids
-maintenance of fluid balance
108
Where is the pituitary gland located?
Located inferior to the hypothalamus
Sits in a concavity of the sphenoid bone in the middle of the skull
109
Physical contact between the hypothalamus and the pituitary gland allow for...
allows for communication between the nervous and endocrine system
110
What are the two lobes that the pituitary gland are divided into?
Anterior (Adenohypophysis)
Posterior (Neurohypophysis)
111
What hormones are in the anterior lobe of the pituitary gland?
-Thyroid stimulating hormone (TSH)
-Prolactin (PRL)
-Adrenocorticotropic Hormone (ACTH)
-Growth hormone (GH)
-Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH)
-Melanocyte Stimulating Hormone (MSH)
112
What hormones are in the posterior lobe of the pituitary gland?
Oxytocin
Antidiuretic Hormone (ADH)
113
What does the thyroid stimulating hormone do?
Acts on the thyroid gland, causing it to release thyroid hormones
114
What does prolactin do?
Induces the mammary glands of the breast to produce milk
115
What does Adrenocorticotropic Hormone do?
regulate the glucocorticoid (steroid) hormone cortisol.
116
What does the growth hormone do?
stimulates growth in cells
117
What does the Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH) do?
Both act on the gonads
They stimulate secretion of estrogen and progesterone, and maturation of oocytes in the ovaries
They stimulate secretion of testosterone and sperm production in the testes
118
What does melanocyte do?
stimulates melanocytes in the skin to produce pigment
119
Where does neurohypophysis get its name?
Known as neurohypophysis because it is made up of nervous tissue
120
What does ADH do?
The general function of ADH is to promote reabsorption of water at the kidneys
121
What does oxytocin do?
The function of oxytocin is to promote uterine contractions during childbirth. It also plays a role in breastfeeding
122
What stains darker, the anterior lobe of the pituitary gland or the posterior?
The anterior
123
What is the anterior lobe of the pituitary gland made up of?
-Glandular tissue
-Made up of glandular acini (small sac-like cavities) that are arranged in small groups that are surrounded by connective tissue
124
What is the posterior lobe of the pituitary gland made up of?
-Composed of nervous and connective tissue
-Does not contain acini
125
What is an important structure in maintaining metabolic homeostasis?
The thyroid gland
126
Where does the thyroid gland lie?
Sits in the neck anterior to the trachea and inferior to the larynx
127
What is the thyroid gland composed of?
Follicles that are lined with simple cuboidal follicular cells.
These surround a central lumen called colloid.
Between the follicles are parafollicular ("C") cells
128
What do the follicular cells in the thyroid gland produce?
Triiodothyronine (T3) and Thyroxine (T4)
Act to increase the rate of metabolism and oxygen consumption
129
What do the C cells in the thyroid gland produce?
The C cells are important in calcium homeostasis
They produce calcitonin - lowers the blood calcium concentration
130
What are the parathyroid glands?
four tiny glands embedded in the back of the thyroid
131
What do the parathyroid glands do?
What do the parathyroid glands do?
132
Where are the adrenal glands located?
on top of the kidneys
133
What structures can the adrenal glands be divided into?
-the cortex
-the medulla
134
What does the adrenal medulla produce?
Produces epinephrine and norepinephrine in response to sympathetic nervous system stimulation resulting in an autonomic (flight or fight) response
135
What are the three layers that the adrenal cortex is divided into? And what do they do?
The outer layer
The middle layer
The inner layer
Collectively they produce two dozen hormones
136
What does the outer layer of the adrenal cortex produce?
Mineralocorticoids
137
What does the middle layer of the adrenal cortex produce?
Glucocorticoids
138
What does the inner layer of the adrenal cortex produce?
Androgens
139
True or false: the pancreas is a mixed gland (has both exocrine and endocrine functions)?
True
140
What do beta cells do?
produce insulin and functions to lower blood glucose levels (hypoglycemic)
141
What do alpha cells do?
produce glucagon and functions to increase blood glucose levels (hyperglycaemic)
142
What does the PNS contain?
-Contains all of the nerves outside of the brain and spinal cord
-PNS contains the spinal and cranial nerves
143
What does the sensory (afferent) system do?
Transmits sensory information from the periphery to the CNS
144
What does the motor (efferent) system do?
Transmits motor commands from the CNS to the periphery
145
What does the somatic nervous system do?
controls voluntary movements
146
What does the autonomic nervous system do?
Involuntary motor control of smooth and cardiac muscle
147
What does the sympathetic nervous system do?
fight or flight
148
What does the parasympathetic system do?
rest and digest
149
How do cranial nerves emerge?
Emerge in pairs from the brain and brainstem instead of the spinal cord
150
How many pairs of cranial nerves are there?
12
151
Nerve I
Olfactory
Sensory only
Smell
152
Nerve II
Optic
Sensory only
Vision
153
Nerve III
Oculomotor
Motor only
Movement of the eye (there's three)
154
Nerve IV
Trochlear
Motor only
Movement of the eye
155
Nerve V
Trigeminal
Sensory - forehead, eye, upper jaw, lower jaw
Motor - muscles of mastication
156
Nerve VII
Facial
Sensory - taste for anterior 2/3 of tongue
Motor - muscles of facial expression, parasympathetic innervation of tear and salivary glands
157
Nerve VIII
Vestibulocochlear
Sensory only
Equilibrium and hearing
158
Nerve IX
Glossopharyngeal
Sensory - sensory innervation of the pharynx, taste from posterior 1/3 of tongue
Motor - pharynx muscles, parasympathetic innervation of salivary glands
159
Nerve X
Vagus
Sensory - sensory innervation of the larynx
Motor - Pharynx and larynx muscles, parasympathetic innervation of the thoracic and abdominal organs
160
Nerve XI
Accessory
Motor only
Trapezius and sternocleidomastoid muscles
161
Nerve XII
Hypoglossal
Motor only
Muscles of the tongue
162
How many pairs of spinal nerves are there?
31
163
How is a spinal nerve formed?
A spinal nerve is formed by the union of the posterior (sensory) and anterior (motor) roots of the spinal cord
164
How are spinal nerves named?
Letter = refers to the region of the spinal cord
Number = refers to the level
165
What are the nerve plexuses?
Once the spinal nerves exit the vertebral column, fibres from the anterior roots (motor) come together and then redistribute into new networks of nerves (plexuses) that mostly innervate muscles of the limb
166
What do the nerve plexuses contain?
Each plexuses therefore contains fibres (a collection of axons) from a combination of spinal nerves
167
What is the functional importance of the nerve plexuses?
In the case of injury, the contribution of multiple spinal nerves into the nerve plexuses ensures innervation to the muscle
168
What nerve plexuses correspond to the cervical enlargement?
The cervical and brachial plexuses correspond to the cervical enlargement
169
What nerve plexuses correspond to the lumbosacral enlargement?
Lumbar and sacral plexuses correspond to the lumbosacral enlargement
170
What does "two neuron pathway" mean?
Between the CNS and any target organ, there are two neurons
171
Between the CNS and any target organ, there are two neurons
The automatic nervous system
172
What is the preganglionic neuron?
-has its cell body within the CNS
-The axon enters into the PNS and travels to the autonomic ganglion
173
What is the autonomic ganglion?
-where the preganglionic and postganglionic neurons meet and communicate
-located in the PNS
174
What is a postganglionic neuron?
-entirely in the PNS
-its cell body is in the autonomic ganglion, while its axon travels to the target organ
